<! and >! are not normal IFn's or applicative function calls. They are akin to special forms or value-less macros compiled by the go macro. Maybe we can improve the docstring to show that those forms can't be applied across its arguments.

>! macro docstring:

puts a val into port. nil values are not allowed. Must be called inside a (go ...) block. Will park if no buffer space is available.

The >! var in clojure.core.async is just a hook to attach some docstring metadata. Its state can be nil and the go macro would still work the same.

Ghadi Shayban
added a comment - 28/Jul/13 10:59 PM <! and >! are not normal IFn's or applicative function calls. They are akin to special forms or value-less macros compiled by the go macro. Maybe we can improve the docstring to show that those forms can't be applied across its arguments.
>! macro docstring:

puts a val into port. nil values are not allowed. Must be called inside a (go ...) block. Will park if no buffer space is available.

The >! var in clojure.core.async is just a hook to attach some docstring metadata. Its state can be nil and the go macro would still work the same.